Manufacturing method of reactor

ABSTRACT

A method of manufacturing a reactor that includes a reactor and a pair of core segments. The method includes mounting the reactor coil onto the pair of core segments, and placing the core segments face to face, with a thermosetting adhesive sandwiched there between. The method further includes placing a heating core such that one end of the heating core around which a heating coil is wound faces one of the core segments, and the other end of the heating core faces the other core segment; producing heat in the core segments by an alternating magnetic flux; and binding together the core segment by a temperature rise and cure of the thermosetting adhesive.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2017-063768 filed onMar. 28, 2017 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

A technology to be disclosed by the present specification relates to areactor manufacturing method and a heating device that is used inmanufacturing reactors.

2. Description of Related Art

A reactor of which a core, around which a coil is wound, is divided intoa plurality of core segments is known. Such core segments are sometimesbonded together with a thermosetting adhesive. For example, JapanesePatent Application Publication No. 2007-335523 (JP 2007-335523 A) andJapanese Patent Application Publication No. 2014-33039 (JP 2014-33039 A)disclose a technique relating to the bonding of core segments using athermosetting adhesive. The technique of JP 2007-335523 A involves thefollowing steps: A coil is mounted onto two core segments, and the twocore segments are placed face to face, with an uncured thermosettingadhesive sandwiched therebetween. This assembly of the two core segmentsand the coil is heated with a heater to allow the thermosetting adhesiveto undergo a temperature rise and cure. As the thermosetting adhesivecures, the two core segments are bonded together. When the assembly isthus heated with a heater, the coil is heated as well. To distinguishthe coil of the reactor from a high-frequency heating coil (to bedescribed later) that heats the reactor, the former will be hereinafterreferred to as a reactor coil. The high-frequency heating coil will bereferred to simply as a heating coil.

JP 2014-33039 A discloses a technique for bonding together core segmentswhile suppressing the temperature rise of a reactor coil. This techniqueinvolves the following steps: A reactor coil is mounted onto two coresegments, and the two core segments are placed face to face, with anuncured thermosetting adhesive sandwiched therebetween. This assembly ofthe two core segments and the reactor coil is disposed inside a heatingcoil. An alternating current is applied to the heating coil, so that theresulting alternating magnetic flux produces heat in the core segments.The heat produced in the core segments allows the thermosetting adhesiveto undergo a temperature rise and cure. As a result, the two coresegments are bonded together. In the technique of JP 2014-33039 A, sucha frequency is selected that the rate of the temperature rise of thecore segments due to the resulting alternating magnetic flux is higherthan the rate of the temperature rise of the reactor coil. Therefore,the technique of JP 2014-33039 A can allow the thermosetting adhesive toundergo a temperature rise and cure by the heat produced in the coresegments, while suppressing the temperature rise of the reactor coil.

SUMMARY

In the technique of JP 2014-33039 A, the heating coil does not have acore. Therefore, the magnetic field generated by the heating coilspreads to a space surrounding the heating coil. Part of the alternatingmagnetic flux generated by the heating coil passes through the windingof the reactor coil. This magnetic flux passing through the winding ofthe reactor coil causes an eddy current and produces heat in thewinding. Thus, the technique of JP 2014-33039 A cannot avoid heat beingproduced in the winding of reactor coil due to the magnetic flux passingtherethrough. There is room for improvement in the method of bondingcore segments of a reactor using a heating coil (reactor manufacturingmethod). The present specification provides an improved manufacturingmethod of a reactor and a heating device suitable for this manufacturingmethod.

An example aspect of the disclosure is a manufacturing method of areactor. The reactor includes a first core segment and a second coresegment. The manufacturing method includes: mounting a reactor coil ontothe first core segment and the second core segment, and placing thefirst core segment and the second core segment face to face, with anuncured thermosetting adhesive sandwiched between the first core segmentand the second core segment; placing a heating core such that one end ofthe heating core around which a heating coil is wound faces the firstcore segment, and the other end of the heating core faces the secondcore segment; producing heat in the first core segment and the secondcore segment by an alternating magnetic flux, the alternating magneticflux being generated in a closed magnetic circuit extending through theheating core, the first core segment, the second core segment, and thethermosetting adhesive by applying an alternating current to the heatingcoil; and binding together the first core segment and the second coresegment by a temperature rise and cure of the thermosetting adhesive.According to this manufacturing method, almost the entire magnetic fluxgenerated by the heating coil passes through the closed magnetic circuitextending through the heating core, the first core segment, the secondcore segment, and the thermosetting adhesive. It is therefore possibleto produce heat in the core segments and bond together the core segmentswhile suppressing the temperature rise of the reactor coil.

An area of a bonding interface between the first core segment and thesecond core segment may be smaller than each of an area of a region ofthe heating core that faces the first core segment and an area of aregion of the heating core that faces the second core segment. Thesmaller the area through which the magnetic flux passes, the higher thedensity of the magnetic flux, which means a larger amount of heatproduced per unit area. When the regions of the heating core that facethe core segments are large, the temperatures of the core segments inthe vicinity of the boundary between the heating core and the coresegments rise slowly, and meanwhile the temperatures of the coresegments in the vicinity of a bonding portion therebetween can be raisedquickly.

A frequency of the alternating current may be a frequency such that aloss in the heating core is smaller than a loss in each of the firstcore segment and the second core segment; and as the alternating currentof the frequency flows through the heating coil, the loss of the heatingcore due to magnetic hysteresis and an eddy current may occur in thefirst core segment and the second core segment. When an alternatingcurrent is applied to the heating coil, a loss (iron loss) due tomagnetic hysteresis and an eddy current occurs in the first core segmentand the second core segment. The amount of heat produced per unit areaof the core is attributable to a loss in the core. The unit area heremeans a unit area orthogonal to a magnetic flux passing through. Theloss in the core depends on the material of the core and the frequencyof the current applied. Selecting such a material of the heating coreand such a frequency of the alternating current that the loss in theheating core becomes relatively small can reduce the loss in the heatingcore, so that the magnetic energy can be effectively used to produceheat in the core segments.

One end of the heating core may be disposed adjacent to a bondingportion between the first core segment and the second core segment; andthe other end of the heating core may be disposed adjacent to thebonding portion between the first core segment and the second coresegment. This configuration can reduce the length of the closed magneticcircuit including the bonding portion (thermosetting adhesive) andincrease the amount of heat produced in the vicinity of the bondingportion. As a result, the thermosetting adhesive can be heated moreeffectively.

A bonding portion between the first core segment and the second coresegment may be located inside the reactor coil. When the bonding portionis located inside the reactor coil, a heater cannot heat the bondingportion without also heating the reactor coil. Thus, the temperature ofthe reactor coil rises. The technique of JP 2014-33039 A cannot avoidheat being produced in the reactor coil as a magnetic flux passesthrough the winding of the reactor coil and an eddy current occurs.Thus, the temperature of the reactor coil rises. By contrast, thereactor manufacturing method disclosed by the present specificationpasses a magnetic flux to the bonding portion through the core segmentsof the reactor, so that most of the magnetic flux does not pass throughthe winding of the reactor coil. Therefore, the reactor manufacturingmethod disclosed by the present specification can efficiently heat thebonding portion (thermosetting adhesive), even when it is located insidethe reactor coil, while suppressing the temperature rise of the reactorcoil.

An example aspect of the disclosure is a heating device that joinstogether a first core segment and a second core segment of a reactorwith a thermosetting adhesive. The first core segment and the secondcore segment are placed such that the first core segment and the secondcore segment face each other with the thermosetting adhesive sandwichedbetween the first core segment and the second core segment. The heatingdevice includes: a heating core having one end of the heating corefacing the first core segment and the other end of the heating corefacing the second core segment; a heating coil wound around the heatingcore; and a controller configured to apply an alternating current to theheating coil such that an alternating magnetic flux is generated in aclosed magnetic circuit extending through the heating core, the firstcore segment, the second core segment, and the thermosetting adhesive,when the heating core faces the first core segment and the second coresegment.

Details and further improvements of the technique disclosed by thepresent specification will be described in “Detailed Description ofEmbodiments” below.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the disclosure will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is an exploded perspective view of a reactor;

FIG. 2 is a perspective view of the reactor set in a high-frequencyheating device;

FIG. 3 is a plan view of the reactor set in the high-frequency heatingdevice;

FIG. 4 is a perspective view of one core segment of the reactor and oneheating core;

FIG. 5 is a graph showing loss characteristics of the core segment andthe heating core;

FIG. 6 is a perspective view of the reactor set in anotherhigh-frequency heating device;

FIG. 7 is a plan view of the reactor set in the same high-frequencyheating device;

FIG. 8 is a perspective view of a double-coil reactor and thehigh-frequency heating device; and

FIG. 9 is a side view of the double-coil reactor and the high-frequencyheating device.

DETAILED DESCRIPTION OF EMBODIMENTS

A reactor manufacturing method of an embodiment will be described withreference to the drawings. First, a reactor 2 that is one example of thereactor manufactured by the manufacturing method of the embodiment willbe described. FIG. 1 is an exploded perspective view of the reactor 2.The reactor 2 includes two E-shaped core segments 3 a, 3 b, and a coil4. The core segments 3 a, 3 b will be collectively referred to as areactor core 3. The two core segments 3 a, 3 b have the same shape. Thecore segments 3 a, 3 b are disposed so that leading end surfaces 33, 34of three straight parts 32, 31 extending parallel to one another of onecore segment face those of the other core segment, with the centralstraight parts 31 passed through an inside of the coil 4.

The leading end surfaces 33 of the right and left straight parts 32 ofthe core segment 3 a are bonded with those of the core segment 3 b. Inother words, the leading end surfaces 33 constitute bonding interfacesbetween the two core segments 3 a, 3 b. The leading end surfaces 33 ofthe right and left straight parts 32 (bonding interfaces) of the twocore segments 3 a, 3 b are bonded together with a thermosettingadhesive, and thus the two core segments 3 a, 3 b are united into onereactor core 3. Of the three straight parts 32, 31 extending parallel toone another, the central straight part 31 is shorter than the right andleft straight parts 32. When the two core segments 3 a, 3 b are bondedtogether, a gap is left between the leading end surfaces 34 of thestraight parts 31 of the two core segments 3 a, 3 b. This gap isprovided to prevent magnetic saturation of the reactor 2.

The core segments 3 a, 3 b are produced by compacting a powder of aferromagnetic material, such as ferrite, with a resin. The coil 4 is anedgewise winding of a rectangular copper wire having an insulatingcoating. Reference signs 41, 42 denote leader lines of the coil 4.Conventional methods can be adopted for the manufacturing method of thecore segments 3 a, 3 b and the manufacturing method of the coil 4, andtherefore detailed description of these manufacturing methods will beomitted.

The core segments 3 a, 3 b offer the following advantages inmanufacturing the reactor 2. The reactor core 3 has a structure in whichboth ends of the part of the reactor core 3 that is passed through thecoil are connected to each other outside the coil. Adopting the coresegments 3 a, 3 b makes it possible to form the coil 4 in advance andthen mount the coil 4 onto the core segments 3 a, 3 b. Adopting such amanufacturing method can reduce the manufacturing cost of the reactor.

The reactor manufacturing method disclosed by the present specificationis characterized by the bonding method of the core segments 3 a, 3 b.This bonding method of the core segments 3 a, 3 b will be described. Asdescribed above, the core segments 3 a, 3 b are bonded together with athermosetting adhesive (thermosetting resin). Before the thermosettingadhesive is cured, the coil 4 is mounted onto the core segments 3 a, 3b. Then, the core segments 3 a, 3 b are disposed closely face to face,with an uncured thermosetting adhesive 6 sandwiched between the leadingend surfaces 33 (bonding interfaces). The assembly of the coil 4 and thecore segments 3 a, 3 b (the reactor 2 with the non-bonded core segments)is set in a high-frequency heating device (heating device). FIG. 2 is aperspective view of the assembly set in a high-frequency heating device10. FIG. 3 is a plan view of the assembly set in the high-frequencyheating device 10. A holder that holds the reactor 2 with the non-bondedcore segments is not shown in FIG. 2 and FIG. 3.

The high-frequency heating device 10 includes two heating cores 12,heating coils 13 respectively wound around the heating cores 12, and acontroller 20. The controller 20 is connected to leader lines of theheating coils 13, and can apply an alternating current to the heatingcoils 13. A support base for the two heating cores 12 is not shown inFIG. 2 and FIG. 3, either. In FIG. 3, the leader lines of the heatingcoil 13 and the controller 20 are also not shown.

The heating core 12 has a U-shape, and is disposed so that one end 12 aof the U-shape faces the core segment 3 a while the other end 12 b facesthe core segment 3 b. The entire leading end surfaces 14 of the heatingcore 12 face the core segments 3 a, 3 b.

The leading end surface 14 of the one end 12 a of the U-shaped heatingcore 12 faces the core segment 3 a and the leading end surface 14 of theother end 12 b faces the core segment 3 b, while the leading endsurfaces 33 of the core segments 3 a, 3 b face each other. The leadingend surfaces 33 of the core segment 3 a and the leading end surfaces 33of the core segment 3 b are parallel to each other, and closely faceeach other with the thermosetting adhesive 6 sandwiched therebetween. Asindicated by the thick dashed lines in FIG. 3, closed magnetic circuitsB1 (closed loops) each extending through the heating core 12, the coresegments 3 a, 3 b, and the thermosetting adhesive 6 are formed. In otherwords, the heating core 12 has a pair of opposed surfaces (the leadingend surface 14 of the one end 12 a and the leading end surface 14 of theother end 12 b) so that, when the heating core 12 faces the core segment3 a and the core segment 3 b, the closed magnetic circuit B1 extendingthrough the thermosetting adhesive 6 is formed by the heating core 12and the core segments 3 a, 3 b.

When the controller 20 applies an alternating current to the heatingcoil 13, a magnetic flux (alternating magnetic flux) is generated in theheating core 12, the core segments 3 a, 3 b, and the thermosettingadhesive 6 along the closed magnetic circuit B1. Since the leading endsurfaces 33 of the core segments 3 a, 3 b closely face each other withthe thermosetting adhesive 6 sandwiched therebetween, only a slightamount of magnetic flux leaks through the gap between the leading endsurface 33 of the core segment 3 a and the leading end surface 33 of thecore segment 3 b. Almost the entire magnetic flux generated by theheating coil 13 passes through the heating core 12 and the core segments3 a, 3 b (and the thermosetting adhesive 6) along the closed magneticcircuit B1, so that the magnetic flux hardly leaks to an outside. Thealternating current flowing through the heating coil 13 causes thealternating magnetic flux to flow through the heating core 12 and thecore segments 3 a, 3 b, and this magnetic flux produces heat in the coresegments 3 a, 3 b. This heat is produced as the magnetic energy that themagnetic flux loses while passing through the core changes into heat.The heat produced in the core segments 3 a, 3 b allows the thermosettingadhesive 6 to undergo a temperature rise and cure. As described above,the magnetic flux generated by the heating coil 13 passes through theheating core 12 and the core segments 3 a, 3 b (and the thermosettingadhesive 6) and hardly leaks to the outside, so that almost no magneticflux passes through the coil 4 of the reactor 2. Therefore, the amountof heat produced in the coil 4 is small, and the temperature rise of thecoil 4 can be suppressed. In other words, it is possible to cure thethermosetting adhesive 6 by efficiently raising the temperature thereofusing the magnetic energy generated by the alternating current in theheating coil 13.

The leading end surfaces 14 of the U-shaped heating core 12 and thereactor core 3 closely face each other across a slight clearance d. Theheating core 12 is thus kept out of contact with the reactor core 3 inorder to prevent damage to the reactor core 3. The clearance d isslight, and the amount of magnetic flux leaking through the clearancebetween the leading end surfaces 14 of the heating core 12 and thereactor core 3 is also slight. In other words, the heating core 12 andthe reactor core 3 are magnetically coupled to each other.

As shown in FIG. 3, the heating core 12 is disposed so that both ends 12a, 12 b are adjacent to the bonding portion between the core segments 3a, 3 b (leading end surfaces 33). With the heating core 12 thusdisposed, the length of the closed magnetic circuit B1 extending throughthe core segments 3 a, 3 b is reduced, so that the temperature of thebonding portion (thermosetting adhesive 6) can be effectively raised.

The alternating magnetic flux, albeit a slight amount, passes throughthe central straight parts 31 (see FIG. 1) of the core segments 3 a, 3b. This means that the alternating magnetic flux passes through theinside of the coil 4. Even when the alternating magnetic flux passesthrough the inside of the coil 4, no current flows through the coil 4,as both ends 41, 42 of the coil 4 are free. Moreover, no magnetic fluxpasses through the winding of the coil 4, so that no eddy current occursin the winding of the coil 4. Therefore, almost no heat is produced inthe coil 4.

FIG. 4 is a perspective view of one core segment 3 a and one heatingcore 12. The leading end surfaces 14 of the heating core 12 face thecore segments 3 a, 3 b. The area of the leading end surface 33 (bondinginterface) of the core segment 3 a is smaller than the area of theleading end surface 14 of the heating core 12 (i.e., the area of theregion of the heating core 12 that faces the core segment 3 a). The coresegments 3 a, 3 b have the same shape, and the area of the leading endsurface 33 (bonding interface) of the core segment 3 b is also smallerthan the area of the leading end surface 14 of the heating core 12 (thearea of the region of the heating core 12 that faces the core segment 3b). This means that the density of magnetic flux in the bondinginterface is higher than the density of magnetic flux at the boundarybetween the heating core 12 and the core segment 3 a (leading endsurface 14). The higher the density of magnetic flux, the larger theamount of heat produced per unit area. Because of this arearelationship, the loss of magnetic energy in the vicinity of theboundary between the heating core 12 and the core segment 3 a isreduced, and the density of heat production in the vicinity of thebonding portion (thermosetting adhesive 6) relatively increases. Thiscontributes to accelerating the temperature rise of the thermosettingadhesive 6.

Next, the frequency of the alternating current applied to the heatingcoil 13 will be described. FIG. 5 is a graph showing the losscharacteristics of the reactor core 3 and the heating core 12. Thevertical axis shows a loss W2, and the horizontal axis shows thefrequency. The dashed-line graph G1 represents the frequencycharacteristics of the loss in the reactor core 3, and the solid-linegraph G2 represents the frequency characteristics of the loss in theheating core 12. In a range lower than the frequency fth, the loss inthe heating core 12 (graph G2) is smaller than the loss in the reactorcore 3 (line G1). The frequency of the alternating current applied tothe heating coil 13 is set to a range lower than the frequency fth. Whensuch a frequency is selected, the amount of heat produced in the heatingcore 12 becomes smaller than the amount of heat produced in the reactorcore 3. This also contributes to effectively raising the temperature ofthe bonding portion (thermosetting adhesive 6). As the alternatingcurrent is applied to the heating coil 13, a loss (iron loss) due tomagnetic hysteresis and an eddy current occurs in the reactor core 3(core segments 3 a, 3 b).

Another example of the high-frequency heating device will be describedusing FIG. 6 and FIG. 7. FIG. 6 is a perspective view of anotherhigh-frequency heating device 110 in which the reactor 2 with thenon-bonded core segments 3 a, 3 b is set. FIG. 7 is a side view of thehigh-frequency heating device 110 in which the reactor 2 with thenon-bonded core segments 3 a, 3 b is set. The leader lines of the coresegments 3 a, 3 b, the controller 20, and a part of the winding of thecoil 4 are not shown in FIG. 7. The high-frequency heating device 10shown in FIG. 2 and FIG. 3 includes the two heating cores 12. Thehigh-frequency heating device 110 shown in FIG. 6 includes onelarge-sized U-shaped heating core 112. The two core segments 3 a, 3 bclosely held together with an uncured thermosetting adhesive sandwichedtherebetween is set on an inside of both leading ends 112 a, 112 b ofthe U-shaped heating core 112. The holder of the core segments 3 a, 3 bthat are closely held together is not shown in FIG. 6 and FIG. 7.

The one end 112 a of the heating core 112 closely faces the core segment3 a, while the other end 112 b closely faces the core segment 3 b. Thecore segments 3 a, 3 b closely face each other with the thermosettingadhesive 6 sandwiched therebetween. As shown in FIG. 7, the coresegments 3 a, 3 b are held on the inside of both ends 112 a, 112 b ofthe U-shaped heating core 112, and a closed magnetic circuit B2 isformed by the heating core 112 and the core segments 3 a, 3 b (and thethermosetting adhesive 6). When the controller 20 applies an alternatingcurrent to a heating coil 113, an alternating magnetic flux is generatedin the closed magnetic circuit B2. This alternating magnetic fluxproduces heat in the core segments 3 a, 3 b, so that the thermosettingadhesive 6 undergoes a temperature rise and cures. As a result, the coresegments 3 a, 3 b are bonded together. Most of the magnetic field(magnetic flux) generated by the heating coil 113 passes through theclosed magnetic circuit B2, and therefore the coil 4 of the reactor 2 ishardly heated.

As described above, the central straight parts 31 (see FIG. 1) of theE-shaped core segments 3 a, 3 b are shorter than the right and leftstraight parts 32, and a gap is left between the leading end of thestraight part 31 of the core segment 3 a and the leading end of thestraight part 31 of the core segment 3 b. The width of the gap is largerthan the width of the thermosetting adhesive 6. The magnetic resistanceof a magnetic path extending through the central straight parts 31 ofthe core segments 3 a, 3 b facing each other is larger than the magneticresistance of a magnetic path extending through the right and leftstraight parts 32. Therefore, not so much magnetic flux flows throughthe magnetic path extending through the central straight parts 31 (i.e.,the magnetic path extending through the inside of the coil 4) as throughthe magnetic path extending through the right and left straight parts32. Moreover, even when an alternating magnetic flux flows through theinside of the coil 4, no inductive current flows through the coil 4, asboth ends 41, 42 of the coil 4 are free. No magnetic flux directly flowsthrough the winding of the coil 4, so that no eddy current occurs in thewinding of the coil 4, either. Since the clearance d between the leadingends 112 a, 112 b of the heating coil 113 and the reactor core 3 issmall, only a slight amount of magnetic flux leaks through thisclearance. Since the thickness of the thermosetting adhesive 6 is small,only a slight amount of magnetic flux leaks through the gap between theleading end surface 33 of the core segment 3 a and the leading endsurface 33 of the core segment 3 b. These factors also contribute tosuppressing the temperature rise of the coil 4.

A manufacturing method of a reactor having a different shape will bedescribed using FIG. 8 and FIG. 9. FIG. 8 is a perspective view of areactor 102 set in the high-frequency heating device 110. Thehigh-frequency heating device 110 is the same device as that describedwith FIG. 6 and FIG. 7. Two core segments 103 a, 103 b that are closelyheld together with uncured thermosetting adhesives 6 a, 6 b and a gapplate 7 sandwiched therebetween, are set on the inside of both leadingends of the U-shaped heating core 112. A holder of the core segments 103a, 103 b that are closely held together is not shown in FIG. 8 and FIG.9.

A core (reactor core 103) of the reactor 102 is divided into the twoU-shaped core segments 103 a, 103 b. When joined together, the coresegments 103 a, 103 b form a ring shape. Two coils 104 a, 104 b arewound around the ring-shaped reactor core 103. The reactor 102 issometimes called a double-coil reactor. Although leader lines of thecoils 104 a, 104 b are not shown, one end of the coil 104 a and one endof the coil 104 b are connected to each other.

In the manufacturing method of the reactor 102, first, the coils 104 a,104 b are mounted onto the core segments 103 a, 103 b of the reactor102, and the core segments 103 a, 103 b are placed closely face to face,with the uncured thermosetting adhesive sandwiched therebetween. Next,the assembly of the core segments 103 a, 103 b and the coils 104 a, 104b (the assembly with the uncured thermosetting adhesive) is set in thehigh-frequency heating device 110.

The bonding portions between the core segments 103 a, 103 b arerespectively located on an inside of the coils 104 a, 104 b. FIG. 9 is aside view of the reactor 102 set in the high-frequency heating device110. In FIG. 9, the coil 104 b is indicated by an imaginary line, andthus the core segments 103 a, 103 b inside the coil 104 b are alsodepicted.

The core segments 103 a, 103 b face each other with the gap plate 7sandwiched therebetween. The leading end surface 133 of the core segment103 a and the gap plate 7 are bonded together with the thermosettingadhesive 6 a, while the leading end surface 133 of the core segment 103b and the gap plate 7 are bonded together with the thermosettingadhesive 6 b. The leading end surfaces 133 of the core segments 103 a,103 b correspond to the bonding interface. The heating core 112 isdisposed so that the one end 112 a faces the core segment 103 a whilethe other end 112 b faces the core segment 103 b.

As shown in FIG. 9, a closed magnetic circuit B3 is formed by theheating core 112 and the core segments 103 a, 103 b. When the controller20 applies an alternating current to the heating coil 113, a loss ofmagnetic energy in the core segments 103 a, 103 b changes into heat, andthus heat is produced. This heat allows the thermosetting adhesives 6 a,6 b to undergo a temperature rise and cure. As a result, the coresegments 103 a, 103 b are bonded together. Most of the alternatingmagnetic flux generated by the alternating current flowing through theheating coil 113 flows through the closed magnetic circuit B3. While oneend of the coil 104 a and one end of the coil 104 b are connected toeach other, the other end of the coil 104 a and the other end of thecoil 104 b are connected to nothing. During the bonding of the coresegments 103 a, 103 b, the coils 104 a, 104 b as an electrical circuitare open. Therefore, even when an alternating magnetic flux passesthrough the inside of the coils 104 a, 104 b, no inductive current flowsthrough the coils 104 a, 104 b. Moreover, as in the above embodiment,almost no alternating magnetic flux flows through the windings of thecoils 104 a, 104 b. Accordingly, almost no heat is produced in the coils104 a, 104 b of the reactor 102.

In the case of a reactor in which the bonding portion between the coresegments is located inside the reactor coil, applying heat to thebonding portion by a heater etc. from the outside ends up raising thetemperature of the reactor coil as well. The manufacturing methoddisclosed by the present specification uses the heat produced in thecore segments to allow the thermosetting adhesive to undergo atemperature rise and cure. Both ends of the reactor coil are free, sothat no inductive current flows through the reactor coil even when analternating magnetic flux passes through the inside of the reactor coil.Most of the alternating magnetic flux generated by the alternatingcurrent in the heating coil passes through the inside of the coresegments, and almost no magnetic flux passes through the winding of thereactor coil. Thus, the temperature rise of the reactor coil can besuppressed. The manufacturing method disclosed by the presentspecification is especially suitable for a reactor in which the bondingposition is located inside the coil.

The following are notes on the technique having been described in theembodiment: The core segments 3 a, 103 a of the embodiment correspond toone example of the first core segment. The core segments 3 b, 103 b ofthe embodiment correspond to one example of the second core segment. Agap plate or another core segment may be sandwiched between the firstcore segment and the second core segment. Thus, the technique disclosedby the present specification is also applicable to the manufacture of areactor having a core that is divided into three or more segments.

The manufacturing method disclosed by the present specification isespecially suitable for the manufacture of a reactor including a core ofwhich both ends of a part passed through a coil are connected to eachother outside the coil. Such a reactor is easy to manufacture in that acoil manufactured in advance can be installed on segments of the core.On the other hand, applying heat to such a reactor from the outside toraise the temperature of the bonding position ends up raising thetemperature of the coil as well. The technique disclosed by the presentspecification uses the heat produced in the core of the reactor to raisethe temperature of the thermosetting adhesive, and therefore cansuppress the temperature rise of the coil.

The reactor manufactured by the manufacturing method disclosed by thepresent specification is not limited to the reactor of the embodiment.Moreover, the manufacturing method disclosed by the presentspecification is not limited to the configuration of the high-frequencyheating devices 10, 110 of the embodiment. In the manufacturing methodof the embodiment, the heating cores 12, 112 and the reactor cores 3,103 are disposed with the clearance d left therebetween. This is toprevent damage to the reactor cores 3, 103. Alternatively, the surfaceof the heating core facing the reactor core may be physically in contactwith the reactor core.

While the specific examples of the present disclosure have beendescribed in detail above, these examples are merely illustrative andnot intended to limit the scope of the claims. The technique describedin the scope of the claims also includes the above-illustrated specificexamples with various modifications and changes added thereto. Thetechnical elements described in the present specification or thedrawings exhibit technical utility independently or in variouscombinations, and are not limited to the combinations described in theclaims at the time of patent application. Moreover, the techniqueillustrated in the present specification or the drawings can achieve aplurality of objects at the same time, and has technical utility simplyby achieving one of these objects.

What is claimed is:
 1. A manufacturing method of a reactor comprising:providing a first core segment and a second core segment; mounting areactor coil onto the first core segment and the second core segment,and placing the first core segment and the second core segment face toface, with a thermosetting adhesive sandwiched between the first coresegment and the second core segment; placing a heating core such thatone end of the heating core around which a heating coil is wound facesthe first core segment, and the other end of the heating core faces thesecond core segment; producing heat in the first core segment and thesecond core segment by an alternating magnetic flux, the alternatingmagnetic flux being generated in a closed magnetic circuit extendingthrough the heating core, the first core segment, the second coresegment, and the thermosetting adhesive by applying an alternatingcurrent to the heating coil; and binding together the first core segmentand the second core segment by a temperature rise and cure of thethermosetting adhesive in response to the heat produced in the firstcore segment and the second core segment so as to manufacture thereactor including the first core segment, the second core segment andthe mounted reactor coil.
 2. The manufacturing method according to claim1, wherein an area of a bonding interface between the first core segmentand the second core segment is smaller than each of an area of a regionof the heating core that faces the first core segment and an area of aregion of the heating core that faces the second core segment.
 3. Themanufacturing method according to claim 1, wherein: a frequency of thealternating current is a frequency such that a loss in the heating coreis smaller than a loss in each of the first core segment and the secondcore segment; and as the alternating current of the frequency flowsthrough the heating coil, the loss of the heating core due to magnetichysteresis and an eddy current occurs in the first core segment and thesecond core segment.
 4. The manufacturing method according to claim 1,wherein: one end of the heating core is disposed adjacent to a bondingportion between the first core segment and the second core segment; andthe other end of the heating core is disposed adjacent to the bondingportion between the first core segment and the second core segment. 5.The manufacturing method according to claim 1, wherein a bonding portionbetween the first core segment and the second core segment is locatedinside the reactor coil.